This invention relates to dry powder inhalers and in particular to dry powder inhalers in which powdered medicament is carried on the surface of a flexible sheet material prior to dispensing.
Asthma and other respiratory diseases have long been treated by the inhalation of appropriate medicament. For many years the two most widely used and convenient choices of treatment have been inhalation of medicament from a drug solution or suspension in a metered dose inhaler (MDI), or inhalation of powdered drug and perhaps excipients from a dry powder inhaler (DPI). With growing concern being voiced over the damage done to the earth's ozone layer by CFC's (chlorofluorocarbons) which are in widespread use in existing MDI'S, heightened interest in DPI systems has been stimulated.
W090/13328 discloses a dry powder inhalation device comprising a housing defining a chamber in communication with a patient port in the form of a mouthpiece or nasal adaptor, and an elongate carrier bearing a powdered medicament, the device being constructed and arranged such that areas of predetermined size of the elongate carrier may sequentially be exposed within the chamber, the device comprising one or more air inlets such that when a patient inhales through the patient port an air flow is established from the air inlet(s) to the patient port through the chamber such that particles of the powdered medicament of respirable size from said exposed area of the elongate carrier are entrained within the air flow.